Rotary carrier method and apparatus for centrifugal casting

ABSTRACT

THE DISCLOSUTE RELATES TO A CENTRIFUGAL CASTING APPARATUS AND PROCESS WHEREIN DIES ARE DISPLACED AROUND A CIRCULAR PATH BETWEEN CASTING AND EJECTION STATIONS BY A CARRIER, THE DIES AND THE CARRIER BEING ROTATABLE ABOUT HORIZONTAL AXES.   D R A W I N G

United States Patent Inventors Appl. No.

Filed Patented Assignee Priority Alan Dearden;

Edgar O. G. Castell; Leslie Hylton, all 01' St. John's Works, Bradford.England 770,507

Oct 25, 1968 June 28, 1971 Hepworth & Grandage Limited Bradford, EnglandOct. 30, 1967 Great Britain ROTARY CARRIER METHOD AND APPARATUS FORCENTRIFUGAL CASTING 11 Claims, 2 Drawing Figs.

US. Cl

Int. Cl

[50] FieldofSearch .1 164/114, 154, 286, 292, 295-298, 323-325, 138

[56] References Cited UNITED STATES PATENTS 2,023,040 12/1935 Adamsl64/298X 2,570,325 10/1951 Dalton... 164/295 2,943,369 7/1960 Szwed[64/154 3,419,066 12/1968 Lorang 164/154X 3,457,986 7/1969 Andrews164/295X 3,486,551 12/1969 Inoye 164/286 Primary Examiner-J. SpencerOverholser Assistant Examiner-12. Spencer Annear Atlorney-Holcombe,Weterill and Brisebois ABSTRACT: The disclosure relates to a centrifugalcasting apparatus and process wherein dies are displaced around acircular path between casting and ejection stations by a carrier, thedies and the carrier being rotatable about horizontal axes.

ROTARY CARRIER METHOD AND APPARATUS FOR CENTRIFUGAL CASTING Thisinvention relates to centrifugal casting.

According to this invention in one aspect, a centrifugal castingapparatus includes, or is adapted to accommodate, a plurality of dies,means to move each die between a casting station and an ejectionstation, means to rotate a die when located at the casting station toeffect centrifugal casting of a molten metal in the die, and means toeject a solidified casting from a die when located at the ejectionstation. The dies, for example, a pair of dies, are preferably locatedwith their rotational axes disposed substantially horizontally, and aremovable around a circular or part-circular path having a horizontalaxis.

According to this invention in yet another aspect, a centrifugal castingprocess includes moving a plurality of rotata ble dies in unison arounda circular path having a horizontal axis, successively to a castingstation whereat each die is rotated to effect centrifugal cast of moltenmetal poured into the die, and then to an ejection station whereat thecasting previously formed within the die is ejected therefrom.

One embodiment of the centrifugal casting machine in ac cordance withthe invention will now be described with reference to the accompanyingdrawings, of which:

FIG. 1 is a diagrammatic plan view, partly in section, of the machine;and

FIG. 2 is a section of the line A-A on FIG. 1.

The machine includes a frame 11 in which is mounted a carrier l2rotatable about a horizontal axis. The frame 11 includes plane end walls13, 14 which are interconnected by the base and by an interconnectingwall 15 which is curved and forms the sides and top of the frame. Thewall 15 is provided with ports for observation.

The carrier includes a shaft 16 mounted in bearings l7, 18 in the endwalls, to allow the shaft 16 to be rotated and also to allow it to bemoved axially for a limited travel. A torque unit 19 mounted on one endwall 14 is connected to the shaft to rotate it between predeterminedangular positions, and a piston-and-cylinder device 20 mounted on thecasing of the torque unit 19 is connected to the shaft 16 to move itaxially for a limited travel relative to the frame 11.

Secured to the shaft 16 are a pair of transverse plate members 21, 22each of which is provided with a pair of apertures 23 on diametricallyopposite sides of the shaft 16, and each aperture contains aninterchangeable liner 23a. The apertures defined by the liners carriedby the plate member 21 are aligned with the corresponding apertures ofthe liners carried by the plate member 22.

When the carrier 12 is in the operating position, the centers of the twoaligned pairs of apertures and the rotational axis of the shaft 16 arein a horizontal plane. The region of one aligned pair of apertures inthis position will be referred to as the pouring and casting station,and that of the other aligned pair of apertures as the ejection station.The carrier 12 carries a pair of cylindrical castiron dies 24, 25, onein each pair of apertures, with a clearance between the outside of thedie and the apertures for a reason which will become apparent, the diesbeing positioned with their axes of rotation disposed generallyhorizontally.

Both ends of the two dies 24, 25 are formed with a conical taper 26; atthe pouring station there are provided a pair of conical members orrings 27a, 28a, one of which 27a will be referred to as the movable coneand the other of which 28a will be referred to as the fixed cone. Therotational axes of these cones are aligned with one another and with thecenters of that aligned pair of apertures 23 and liners 23a located atthe pouring and casting station.

The movable cone 27a forms part of an assembly, indicated generally at27, and in particular, is interchangeably mounted on three equiangularlyspaced pillars or webs 27b rigid with a base plate 270 mounted on ashaft rotatable by an electric motor 29. This assembly and motor 29 areaxially movable with respect to end wall 14 by means of a pneumatic ramdevice 30. The motor 29 may be mounted in suitable slides on the base.The fixed cone 28a is likewise interchangeably mounted on threeequiangularly spaced pillars or webs 28b rigid with a base plate 28ccarried by a shaft rotatably mounted in a bearing carried by end wall13, so as to be fixed against axial movement. The fixed cone 28a, itsbase plate 280 and mounting shaft have a large-diameter hollow bore, anda tipping ladle 31 for the molten metal to be cast is mounted to bemovable so that its spout 32 can be advanced through this hollow bore,beyond the cone 28a, and inclined in order to pour the metal within thedie 24. The cone angles of the movable cone 27a and of the fixed cone28a are such as to cooperate with the conical tapers 26 in the ends ofthe dies.

At least the surfaces of the cones 27a, 28a which are likely to comeinto contact with molten metal during casting, and in particular toconical surfaces, and the opposed inwardly directed faces thereof, arepreferably coated with a deposit of a material which prevents orminimizes the adhesion of the cast metal to the cones, for example, a0.005 inch thick plating of industrial chromium.

At the ejection station there is provided an ejector in the form ofadisc 34 mounted on the end of the rod ofa linear actuator 35 and havinga diameter smaller than the internal diameter of the dies; the centralaxis of the disc 34 and actuator 35 is spaced slightly below thehorizontal plane containing the axis of rotation of the carrier 12,because at this station the die 25 rests on the surface of the apertures23 in the transverse plate members 21, 22, and is therefore notconcentric with the apertures. The disc 34 can be advanced forsubstantially the whole length of the die 25, to horizontally eject asolidified casting from the die. For this purpose an aperture 36 isprovided in the end wall 13, and a platform 37 is conveniently providedon the outside ofthe end wall to receive the casting.

The rod of actuator 35 is hollow and is arranged to be fed with a supplyof compressed air when it leaves its position of rest and is advancedthrough the die, by means, for example, of a port which is brought intoregister with a suitable air source. The interior of the rod isconnected to small holes, or jets, 38 in the periphery of the disc 34,so that substantially the whole interior of the die 25 is swept withcompressed air during the ejection stroke.

Adjustable stop means are provided in order to prevent the dies frombeing displaced horizontally with the castings during ejection. Thesemeans comprise three blocks 39 carried by stub shafts 40 journaled inthe end wall 13 around the hole 36. Mounted on each stub shaft 40outside the end wall is a double-ended lever 41, one end of which isconnected to its associated block 39 by a support arm 42, and the otherend of which is apertured to locate on a selected one of a number offixed pins 43 carried by a plate 44 secured to the end wall 13. It willthus be apparent that each lever 41, and therefore each block 39 may beadjusted in inclination, by predetermined amounts, thus adjusting thedistance by which the blocks project, into the space between the hole 36and adjacent end of the die 25.

A fluid logic unit, diagrammatically indicated at 33A, 33B is providedfor the purpose of detecting whether or not a casting, aftersolidification, has detached from the fixed cone 280 or not, onwithdrawal of the die 24 in carrier 12. The unit may include an airemitter 33A, and a receiver 338, which will detect the jet from theemitter 33A provided the casting has detached correctly; if the jet isobliterated by the casting, the receiver 338 will provide appropriateaction for example, will prevent continuation of the casting sequenceuntil the fault is rectified.

The operation of the machine will be described assuming that the carrier12 has just been rotated to bring the die 24 of the two dies to thepouring and casting station.

The carrier 12 is then moved forward (to the right as shown in FIG. 1)by the piston-and-cylinder device 20 to ensure that the die 24 overlapsthe fixed cone 28a. The assembly including the movable cone 27a anddriving motor 29 is then moved forward (to the right as shown) to engagethe tapers 26 on the ends of the die 24 on the respective fixed andmovable cones 27a, 28a in doing so the die 24 is moved from the positionin which it rests in the carrier 12 upward to a position in which it isconcentric with the axis of rotation of the cones 27a, 28a. The movementof the assembly including movable cone 27a starts a short second)timedelay device, which device, at the end of the time delay, closes acontactor in circuit with motor 29.

The motor 29 is energized, and rotates the die 24, the drive beingtransmitted as a result of the die being gripped between the fixed andmovable cones 27a, 28a of which the movable cone 27a is driven by themotor 29. The operator then dresses the die manually with a suitabledressing, ofa type well known in the art, by inserting a tube throughthe hollow bore of the fixed cone 28a, and upturning the tube to depositthe dressing within the rotating die 24.

The ladle 31 which contains the molten metal is then advanced, by theoperator, the spout 32 passing through the hollow bore of the fixed cone28a, and the molten metal is poured. The spout 32 is then withdrawn, andthis action may start a timing device which is set to allow time forsolidification of the metal. Alternatively the operator may start thetiming device manually by means ofa pushbutton. I

At the end of the timed period, when the metal has solidified, the motor29 is automatically stopped and a magnetic brake applied. The movablecone 27a and motor 29 are then retracted by pneumatic ram 30, and thecarrier 12 is moved back by the piston-and cylinder device to ensurethat the die 24 is free of the fixed cone 28a and is clear thereof. Thisenables the die 24, containing the casting, to move down and rest on thelower surface of the apertures in the liners 23a carried by the members21, 22 of the carrier 12.

An interlock is provided to ensure that the movable cone 27a is notremoved until rotation has ceased; moreover the fluid logic device 33A,33B ensures that the casting has freed itself from the fixed cone. lfthis has not occurred, the next stage of the operation cannot takeplace.

The carrier 12 is then rotated by the torque unit 19 to bring the die 24to the ejection station, i.e. to the position in which the die is shownin the drawings. Arrival of the die 24 at this station initiates asecond timing device (for example by closing a switch) which allows ashort cooling period for the casting at the ejection station to contractaway from the die 24 before ejection.

Under control of the second timing device, the ejector 34 is movedoutward by the actuator 35 to eject the solidified casting from the die24 at the ejection station between the blocks 39 and through theaperture 36 in the end plate 13 of the frame onto the platform 37 fromwhich it is removed by the operator. The die 24 is prevented from movingtowards the aperture 36 during ejection by abutment of the die with theend faces of the blocks 39. Compressed air is ejected from the jets 38on the periphery of the ejector disc 34 at the same time as the ejectoris advanced, to clean the interior of the die 24, and the ejector 34 isthen retracted again.

The carrier 12 is now free to rotate to bring the die 24 back to itsinitial position at the pouring and casting station (i.e. to theposition in which die 24 is shown in FIG. 1).

Since the cones 27a, 28a, are coated with chromium, to which the castmetal is not prone to adhere, the likelihood of the solidified castingadhering to one or both cones is eliminated or reduced. Moreover, due tothe fact that the cones are formed'as rings, and are mounted on, butspaced from, their associated base plates 27a, 280, by pillars 27b, 28c,cooling air is free to circulate around these components, therebysubstantially reducing detrimental transfer of heat from the die to theshafts carrying the base plates, and their associated journals.

The apparatus hereinbefore described is particularly compact, due to thefact that the dies move around a circular path between stations. It maybe operated continuously and automatically, and enables castings to beproduced at a high rate. The ejection of the finished castings onto theplatform 37 renders the apparatus particularly suitable forincorporation in an automatic system or production line.

The apparatus may be readily adapted to accommodate dif-. ferentdiameters of dies, by exchanging the cones 27a, 28a, by different sizecones, and by replacing the liners 23a by liners having differentinternal diameters, i.e. internal diameters slightly larger than theexternal diameters of the replacement dies, so that the dies will notbind in the liner due to thermal expansion ofthe dies during casting.

The inclination of the blocks 39 at the ejection station may be adjustedso that their radially inner tips engage the ends of the replacementdies, but do not extend into the path of castings ejected therefrom,during operation of the apparatus. These blocks 39 are swung out of theway during removal and replacement of the dies, which is effectedthrough the aperture 36.

It will be understood that the arrival of one die at the ejectionstation is simultaneous, in the embodiment described, with the arrivalof the other die at the pouring and casting station; thus the sequenceof operations at the ejection station, as just described, takes placeconcurrently with the sequence of operations at the pouring and castingstation which were described above.

Although the machine has been described as having two dies 24, 25 itwill be evident that the carrier 12 might be arranged to have, forexample, four pairs of aligned apertures 23, each carrying a die. Insuch an arrangement the stations could be arranged at intervals ofrotation of the carrier 12, and the two stations between the pouringstation and the ejection station might be employed to provide a coolingperiod for the casting. in this way time delays at the pouring andejection stations may be reduced. If desired, pouring of the moltenmetal, and rotation of the die to effect centrifugal casting, may beeffected at different stations instead of the same stations asspecifically described.

Although, as will be apparent from the arrows in H6. 2, the carrier inthe embodiment specifically described is rotated in a single direction,for example, clockwise as viewed in FIG. 2, the carrier may be rotatedin the opposite direction, or oscillated back and forth between thestations.

We claim:

1. Centrifugal casting apparatus including a plurality of diesconstrained to move in unison along a generally circular path, between acasting station and an ejection station, by a carrier rotatable about agenerally horizontal axis, means to rotate a die about an axis generallyparallel to the rotational axis of the carrier, when the die is locatedat the casting station, to effect centrifugal casting of molten metal inthe die, and means to eject a solidified casting from a die when locatedat the ejection station, the carrier being provided with apertureswithin which the dies are loosely cradled, the apparatus furtherincluding die support means at the casting station, rotatable by thedrive means, and adapted to releasably support a die at each endthereof, the support means comprising a pair of members each having aconical surface cooperable with a corresponding end surface of the die,means for'displacing said conical members toward each other to clamp andsupport the die therebetween, the axis of a die, when cradled by thecarrier at the casting station, being disposed below the axis ofrotation of the conical members, the conical surfaces of the conicalmembers upon clamping of the die, cooperating with the end surfaces ofthe die to lift the die out of contact with the carrier to a position inwhich said axes are coincident, and also to transmit to the die,rotation imparted by the drive means to the support means.

2. Apparatus as claimed in claim 1, wherein the conical members aredimensioned to fit into the ends of the die and to cooperate withcorrespondingly tapered internal end surfaces of the die.

3. Apparatus as claimed in claim 2, wherein the first of said conicalmembers is coupled to an electric drive motor to rotate the die, and thesecond of said conical members is axially fixed but freely rotatable,and provided with an axial passage extending therethrough, means beingprovided to pour molten metal into a die during rotation thereof at thecasting station, through the passage.

4. Apparatus as claimed in claim 3, wherein the first conical member andits drive motor, are bodily reciprocable, by means of a hydraulic ram,to axially advance or withdraw said first conical member relative to thedie and second conical member.

5. Apparatus as claimed in claim 4, wherein the carrier is axiallyreciprocable relative to the second conical member to advance orwithdraw a die cradled by the carrier at the casting station, relativeto the second conical member.

6. Apparatus as claimed in claim 5, wherein each conical membercomprises a ring, at least those surfaces thereof which come intocontact with molten metal during casting being coated with chromium, thering being detachably mounted on pillars carried by a base platerotatably supported by the apparatus frame in journals, said pillarsspacing the ring from its associated base plate, whereby heat transferfrom the ring to the journals during operation of the apparatus isminimized.

7. Apparatus as claimed in claim 6, wherein the carrier is adapted tocarry two demountable and interchangeable dies located in a generallydiametrically opposed relationship on opposite sides of the rotationalaxis of the carrier, and comprises a shaft journaled in the frame of theapparatus, about the axis of which the carrier is rotatable, a pair oftransverse plate-members secured to and spaced along the shaft, eachplate-member being provided with a pair of apertures or diametricallyopposed sides of the shaft, the apertures in one plate-member beingaligned with corresponding apertures in the other plate-member, and eachaperture containing a detachable and interchangeable annular liner.

8. Apparatus as claimed in claim 7, wherein the casting and ejectionstations are disposed in a common horizontal plane.

9. Apparatus as claimed in claim 8, wherein an ejector ram is located atthe ejection station, adapted to enter one end ofa die when located atsaid station to eject a solidified casting therefrom and through anaperture in the frame of the apparatus, stop means being providedadapted to engage a die to prevent displacement thereof with the castingduring ejection, said stop means comprises a plurality of stopsjournaled in the frame at spaced positions around the aperture forswinging movement toward and away from the axis of the die, the stopsprojecting between the die and aperture.

10. Apparatus as claimed in claim 9, adapted for automatic repetitiveoperation, said apparatus including control means, to synchronize andcontrol the operating cycles of the various components of the apparatus,including a casting sensing means at the casting station operable andadapted to prevent rotation of the carrier upon detection of asolidified casting adhering to one of the conical members, said sensingmeans comprising a fluid logic unit including an air emitter and areceiver associated therewith, the receiver being screened from theemitter unless a space exists between the fixed conical member and thedie or a solidified casting therein.

11. A centrifugal casting process, including moving a plurality ofrotatable dies in unison around a circular path having a horizontalaxis, successively to a casting station whereat each die is rotatedabout an axis parallel to said horizontal axis to effect centrifugalcasting of molten metal poured into the die, and then to an ejectionstation whereat the casting previously formed within the die is ejectedtherefrom, the die being loosely cradled, and carried around thecircular path, on a carrier, each die, when at the casting station,being releasably clamped by its opposite ends between a pair ofrelatively axially displaceable conical members of die support meanslocated at the casting station, raised out of engagement with thecarrier, as a result of the clamping action, rotated about itsrotational axis via the die support means, whilst molten metal is pouredthereinto through one end of the die, the rotation then being stoppedand the die replaced on its carrier prior to transfer by the carrier tothe ejection station.

